File Format of Google's Disavow Links Text File

You can learn about Google's Disavow Tool at plenty of sites. Know it for sure that only "Dofollow" links(i.e., those <a tags without rel="nofollow" attribute) pass link juice. Similarly if misused they can bring penalty to the backlinked page(s) or to the whole site.

Google Penguin update especially penalizes based on this theory.

How you disavow?

In Bing you'll need to add a URL, Subdirectory or domain/subdomain one by one.

In Google you'll need to prepare a text file with .txt extension and save toxic URL's. If you want Google to discount all URLs from a domain or sub-domain then use this format:

Remember these two are completely different and mutually exclusive: